There are many reasons why people shed tears. Babies want to manipulate with it. And some adults believe that tears reduce stress levels. However, science so far has few research results to weep.
Crying is a primal human trait. Estimates of how many tears a person sheds over a lifetime range from 70 to 100 liters, or 4.2 to 5 million tears. Despite these veritable streams of tears, research in this area is surprisingly manageable. A review paper, the results of which were published in the journal “Psychotherapy”, found in 2021 that the topic “received surprisingly little attention from behavioral scientists and physicians” and that “empirical research on emotional crying is still in the early stages”.
Ad Vingerhoets, one of the main authors of the study, suspects a misjudgment as the cause of the scientific disinterest: “Tears are often only seen as a sign of sadness.” For the psychologist from Tilburg University in the Netherlands, who has been researching why people cry for 20 years, these represent a very unique form of communication: “They not only contain a lot of information about our current condition, but also about us as a person .”
Only humans seem to shed tears, at least in response to intense emotions. There are repeated reports of crying animals, such as sheep on the slaughterhouse or stressed elephants. But so far it has not been scientifically clarified whether emotions are also associated with this crying. The reptiles only shed the proverbial crocodile tears because they wheeze heavily while eating. Air is pressed so hard through the nasal cavities that it causes the tear ducts to empty – similar to how a person sometimes gets wet eyes when yawning.
In addition to the emotional tears that flow with grief, loss or joy, two other types of tears in humans are known to science: The reflex tears that are caused by external stimuli, such as peeling onions or by wind. Basal tears, on the other hand, are formed to moisturize and cleanse the eyes. All three types of tears consist of water, electrolytes and proteins – but in different concentrations. Emotional tears contain more proteins than reflex tears, as well as higher levels of the hormone serotonin, the trace element manganese and the mineral potassium, and in women the hormone prolactin.
One possible answer to the question of why we humans cry is: manipulation. In a 2007 study, a British researcher reported that babies as young as six months old used tactical crying to get their parents’ attention. According to Vingerhoets, it is precisely in this phase of life that there is a possible evolutionary explanation for emotional tears: Scientists agree that human crying goes back to so-called “separation calls”, which can be observed in all mammals and many birds.
In human offspring, after about a month, the visual signal of tears is added to the acoustic call, which is emitted in all directions. This addition makes evolutionary sense, since human babies, who are particularly dependent on adults for a particularly long time, can use this method to draw attention to themselves without attracting potential aggressors.
However, people continue to cry as adults, long after they have left this childhood form of helplessness behind. Vingerhoets cites a whole range of causes as triggers for these tears, such as loss, conflict, loneliness, defeat, helplessness and pain. Over time, each of these negative triggers will have a positive counterpart that could also make you cry. For example, the birth of a child would stand in the way of loss or death, marriage or reunification would stand in the way of separation. “Those positive tears could be related to a feeling of being overwhelmed, which is ultimately also a form of helplessness,” the psychologist speculates. At the same time, the meaning of the triggers changes over time: While loss and helplessness remain important as causes throughout life, physical pain leads less and less to crying with age.
And there are gender differences: According to the German Ophthalmological Society (DOG), adult men cry 6 to 17 times a year. Women, on the other hand, come to 30 to 64 times – so on average about four to five times more often. The length of the crying also differs: while men let their tears roll for two to four minutes, it is six minutes for women. These differences only arise with age; Up until about the age of 13, boys and girls cry the same amount and for the same reasons.
“When it comes to the big triggers for tears – sadness, homesickness, lovesickness – we hardly see any differences between men and women,” explains Vingerhoets. In everyday situations, however, there are striking differences: “Everyday problems, criticism and above all conflict situations lead to tears in women, but not in men.” In part, this may be due to an internalized sense of powerlessness in women. Conversely, men are often afraid of this emotion and would avoid such situations.
Another role played by the different upbringing, in which tears were less accepted among boys. “And finally, the testosterone in men could ensure that the threshold for crying is higher,” says the psychologist. Several studies would suggest this hormonal connection. However, Vingerhoets is questioning the results of an Israeli study, according to which testosterone levels in men drop when they smell women’s tears. “We have tried unsuccessfully to reproduce the study results with a larger number of participants,” says Vingerhoets.
The psychologist also doubts the supposedly healing power of tears: “In order for people to feel better after crying, various factors must be met, such as a stable overall mental state.” According to several studies, depressed people, for example, do not experience crying as helpful. The triggers also played a role: “Crying because of an uncontrollable situation such as the death of a loved one does not bring relief.”
But the most important thing is the reaction from outside: “Of course you feel better when you get emotional support from those around you.” Last but not least, other coping strategies are often associated with the tears: “But then, in case of doubt, the chocolate ice cream that I treated myself to and the time that elapsed helped and not the crying.”
The belief that crying is liberating can also be traced back to a publication by the US biochemist William Frey, who claimed in the early 1970s that tears primarily flush stress hormones out of the body and thus relieve it. Several studies have refuted this statement: Although it is possible to excrete certain substances through tears, the amount is negligible, writes the doctor Elisabeth Messmer from Munich’s Ludwig Maximilian University in an overview on the subject. Similarly, Ad Vingerhoets doesn’t believe that suppressing crying is unhealthy. This only applies if the general suppression of emotions is an expression of a more fundamental personality problem.
In fact, a comparison between people who never or rarely cry and those who tear more often did not reveal any differences in well-being. Differences emerged in that those who cried felt more empathetic and experienced more social support – an observation that gives Vingerhoets another clue to the function of crying: “Tears bind and form a social glue.” However, what exactly happens in the brain during emotional crying has not yet been answered. It is also unclear whether positive tears differ qualitatively from negative ones.
Vingerhoets would also like to scientifically focus on the personality of people who cry regularly. Because so far, research has focused on how they are perceived: “Through our studies, we found out that people who cry are perceived as warm, honest and reliable and not as weak or unstable, as it is often said.” However, it is unclear whether these ascribed characteristics correspond to reality: “The ancient Greeks said that only good people cry – I wonder if there is a kernel of truth in that.”